Phased radar arrays for use in radar, and particularly for use in the UHF frequency band, between about 300 megaHertz and about 1000 megaHertz, ordinarily take the form of a ground plane having radiating elements that extend through and beyond both sides of the ground plane. The radiating elements typically take the form of dipole antennas or flared notch antennas. A radome is ordinarily provided over the array beyond the radiating elements to provide protection from the weather and contaminants.
For various applications, minimizing the size and weight of phased radar arrays for use in radar bands is important. For example, for some applications, it is desirable to transport ground-based radar antenna arrays by air or ground to a particular location. Antenna arrays with dipole antennas or flared notch antennas extending beyond the ground plane occupy a large volume. As folding of the array is limited by the elements extending through both sides of the ground plane, it is not practical to fold such arrays to reduce the volume for transport. The weight of the radome adds to the weight of the ground plane and antenna elements.
While the radiating element may be a waveguide, thereby not extending beyond the ground plane, prior art waveguides, for example in the UHF band, are much larger than notch arrays or dipole antennas. Accordingly, antenna arrays using prior art waveguides for the UHF band are significantly heavier, larger, or both heavier and larger, than arrays using flared notch antennas, and are thus less desirable.